The present invention relates generally to pumps and, more particularly, to a system and method for detecting cavitation in pumps driven by an electric motor.
Cavitation occurs in pumps when the available net positive suction head becomes less than the required head. During cavitation, the suction pressure is less than the vapor pressure of the liquid, thus causing the liquid within the pump to vaporize and form small bubbles of gas. As the vapor bubbles travel away from the eye of the pump, the pressure rises and compresses the vapor, which causes the vapor bubbles to collapse or implode and typically send very strong local shock waves in the fluid. The energy present in the shock waves often damages the impeller by causing pitting on the surface of the vanes of the impeller. The pitting caused by the collapse of the vapor bubbles produces wear on components and can cause premature failure of the pump. Cavitation also reduces the flow-rate of the pump, thereby negatively affecting operation of the pump.
Existing methods for detecting cavitation have included the use of various types of sensors, such as a combined use of vibration and pressure sensors or hydrophones. While these sensors may aid in determining operating characteristics of the motor/pump system, they typically must be installed within the process framework or the pump system and add complexity and additional cost to the pump system. Still other techniques have focused on current signature analysis with fuzzy-expert systems and neural networks. These methods require complex signal processing to detect cavitation.
It would therefore be desirable to design a system and method for detecting pump cavitation that eliminates the need for additional sensors and complex signal processing.